Well, since you asked for it, I thought I'd mention that bullet-proof
vests
made of kevlar would be very ineffective against predators. Kevlar stops
bullets by spreading out the energy. Kevlar provides almost no protection
against knifes, or in the case of animals, teeth or claws, as the threads
are cut quite easily.

I wonder about the structure of knife-proof bulletproof vests -- which have
been existing for a few years now.